I turn 58 on Monday. Started aikido just under two years ago and haven't had a minute's regret. I train four and sometimes five days a week and get the occasional bruise or soreness, but have no trouble. We have some young studs who are extremely flexible, immortal, and indestructible and I don't try to emulate them, but rather the sempai who are quiet and soft in thier ukemi. My biggest problem is coming home amped up from a class and not being able to sleep for several hours. Give it a try and see if you enjoy it. Your age is no barrier by itself.